rentabilidade_real

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations, the description carries the full burden. It discloses the formula and states that rates are in % per year, which is useful. However, it does not describe the output format (e.g., returns a percentage number), rounding, or error handling. It adds some behavioral context but leaves significant gaps.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is two sentences, front-loaded with the core purpose, then the formula, then the unit convention. No fluff or repetition—every word earns its place.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a simple two-parameter calculation tool with no output schema, the description gives the formula and units but does not specify what the returned value represents (percentage, decimal) or any edge-case behavior. It is adequate for basic use but not fully complete for an agent needing precise expectations.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 0%, so the description must compensate. It clarifies that both parameters are annual rates and in percent, and the Fisher formula reveals their relationship. This adds meaning beyond the parameter names, which are already fairly descriptive. It does not explicitly define each parameter, but the formula and unit mention cover the essentials for two simple parameters.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool's function: 'desconta a inflação (IPCA) da taxa nominal' (discounts IPCA inflation from the nominal rate), and provides the Fisher formula. This is a specific verb-resource pair that distinguishes it from siblings like 'rentabilidade_vs_cdi' or 'converter_taxa'.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description implies usage—when a real (inflation-adjusted) return is needed from a nominal rate and IPCA—but does not explicitly state when NOT to use it or mention alternatives. It provides context but no exclusions or comparisons with sibling tools.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.